# CVE-2021-47936: Opencats OpenCATS remote code execution via resume upload

Source: https://junglewise.ai/threats/cve-2021-47936-opencats-opencats-remote-code-execution-via-resume-upload  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-10. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2021-47936 · Severity: critical · CVSS 9.8 · Published 2026-05-10

OpenCATS, an open-source applicant tracking system used by recruitment teams, contains a critical security flaw in its job application portal. An unauthorized person can upload a malicious file disguised as a resume to take complete control of the server. This could lead to the theft of sensitive candidate data, total service disruption, or the use of the server for further attacks.

Technologies: [OpenCATS](https://junglewise.ai/threats/technologies/opencats). Vendors: [OpenCATS](https://junglewise.ai/threats/vendors/opencats).

## Quick answers

**Is CVE-2021-47936 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-47936 being exploited in the wild.

**How severe is CVE-2021-47936?** Critical severity, with a CVSS score of 9.8, published 10 May 2026.

**Which products and versions are affected?** OpenCATS <= 0.9.4.

**Is there a fix for CVE-2021-47936?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2021-47936 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2021-47936?** Check whether you run OpenCATS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A remote code execution (RCE) vulnerability exists in OpenCATS versions 0.9.4 and earlier due to insufficient validation of uploaded files and missing authentication on critical functions (CWE-306). An unauthenticated attacker can exploit the 'careers' job application endpoint to upload a PHP payload disguised as a resume. Once uploaded, the file is stored in a predictable web-accessible directory (e.g., /upload/careerportaladd/), allowing the attacker to execute arbitrary system commands by sending POST requests to the uploaded file. A public exploit script is available, and users are advised to upgrade to version 0.10.0 or later.

## Affected products

- Opencats OpenCATS <= 0.9.4

## Timeline

- 2021-09-21: other: Vulnerability discovered/Exploit authored
- 2021-12-10: disclosed: Exploit published on Exploit-DB
- 2026-05-10: advisory: NVD/VulnCheck advisory published

## References

- [https://github.com/opencats/OpenCATS](https://github.com/opencats/OpenCATS)
- [https://www.exploit-db.com/exploits/50585](https://www.exploit-db.com/exploits/50585)
- [https://www.opencats.org/](https://www.opencats.org/)
- [https://www.vulncheck.com/advisories/opencats-remote-code-execution-via-resume-upload](https://www.vulncheck.com/advisories/opencats-remote-code-execution-via-resume-upload)

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